DOT HS 811 325
May 2010
Children Injured in
Motor Vehicle Traffic Crashes
DISCLAIMER
This publication is distributed by the U.S. Department of Transportation, National Highway
Traffic Safety Administration, in the interest of information exchange. The opinions, findings,
and conclusions expressed in this publication are those of the authors and not necessarily those
of the Department of Transportation or the National Highway Traffic Safety Administration.
The United States Government assumes no liability for its contents or use thereof. If trade names,
manufacturers’ names, or specific products are mentioned, it is because they are considered essential
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Technical Report Documentation Page
1. Report No.
2. Government Accession No.
3. Recipient’s Catalog No.
DOT HS 811 325
4. Title and Subtitle
5. Report Date
Children Injured in Motor Vehicle Traffic Crashes
May 2010
6. Performing Organization Code
NVS-421
7. Author:
8. Performing Organization Report No.
Refaat Hanna
9. Performing Organization Name and Address
10. Work Unit No.
11. Contract of Grant No.
13. Type of Report and Period Covered
Office of Traffic Records and Analysis
12. Sponsoring Agency Name and Address
NHTSA Technical Report
January 1999- December 2008
Office of Traffic Records and Analysis
National Center for Statistics and Analysis
National Highway Traffic Safety Administration
U.S. Department of Transportation
1200 New Jersey Avenue SE., Washington, DC 20590
14. Sponsoring Agency Code
15.Supplementary Notes
16. Abstract
Objectives: This study analyzes the incidence rates of incapacitating injuries as well as the commonly injured body regions
among children under 8 years old involved in motor vehicle traffic crashes.
Method and Data Source: This study provides a statistical analysis of two different databases: the National Automotive
Sampling System (NASS) General Estimates System (GES) for 1999 to 2008 and the National Trauma Data Bank- National
Sample Project (NTDB-NSP) for 2003 to 2007.
Results: This analysis indicates that use of child safety seats is effective in reducing the incidence rates of incapacitating
injuries for the three age groups and in any crash type. The analysis indicates that children involved in rollover crashes had the
highest incidence rates of incapacitating injuries. In rollover crashes, the estimated incidence rate of incapacitating injuries
among unrestrained children was almost three times that for restrained children. In near-side impacts, unrestrained children
were eight times more likely to sustain incapacitating injuries than children restrained in child safety seats.
Head injuries were the most common injuries sustained by children in motor vehicle crashes. Children under 1 year old had
higher incidence rates of head injuries than the other two age groups. Similar to head injuries, children under 1 had higher
incidence rates of thoracic injuries than the other two age groups.
Cerebrum injuries (contusions or lacerations) were the most common type of head injuries among all children included in the
analysis. Concussion and unconsciousness were more common among children under 1 year old than the other two age groups.
Skull base fractures were more common among children 1 to 3 and 4 to 7 years old than children under 1.
Children under 1 were more likely to sustain rib fractures than the other two age groups. On the other hand, lung injuries
(contusions or lacerations) were more common among older children than children under 1 year old.
17. Key Words: AIS, Children, Child Safety Seat, Head Injury, Incapacitating Injuries, Initial
Point of Impact, Rollover
18. Distribution Statement
Document is available to the public from the National
Technical Information Service www.ntis.gov
19. Security Classif. (of this report)
20. Security Classif. (of this page)
Unclassified
Unclassified
21. No of Pages
27
Form DOT F1700.7 (8-72)
Reproduction of completed page authorized
i
22. Price
TABLE OF CONTENTS
Executive Summary ................................................................................................................................... 1 Objective..................................................................................................................................................... 2 Introduction ................................................................................................................................................ 2 Data and Methodology ............................................................................................................................... 2 Results ........................................................................................................................................................ 4 Analysis of Police-Reported Crashes (NASS-GES) ................................................................................... 4 Seating Position of Children in Vehicles .................................................................................................... 4 Injury Severity ............................................................................................................................................ 6 Incidence of Incapacitating Injuries in Different Crash Scenarios: ............................................................. 6 Injury Severity by Initial Point of Impact (IPI) ........................................................................................... 7 Injury Severity by Restraint Use ............................................................................................................... 10 Injury Severity by Restraint Use and Initial Point of Impact (IPI)............................................................ 12 Analysis of NTDB-NSP Data ................................................................................................................... 15 Injuries by Body Region ........................................................................................................................... 16 Injury Diagnosis ........................................................................................................................................ 18 Head Injuries ............................................................................................................................................. 18 Thoracic Injuries ....................................................................................................................................... 18 Abdominal Injuries ................................................................................................................................... 19 Upper Extremity Injuries .......................................................................................................................... 19 Lower Extremity Injuries .......................................................................................................................... 20 Conclusion ................................................................................................................................................ 21 References ................................................................................................................................................. 22 ii
EXECUTIVE SUMMARY
Objectives: This study analyzes the incidence rates of incapacitating injuries as well as the
commonly injured body regions among children under 8 years old involved in motor vehicle
traffic crashes.
Method and Data Source: This study provides a statistical analysis of two different databases,
the National Automotive Sampling System (NASS) General Estimates System (GES) for 1999 to
2008 and the National Trauma Data Bank-National Sample Project (NTDB-NSP) for 2003 to
2007.
Results: This analysis indicates that use of child safety seats is effective in reducing the
incidence rates of incapacitating injuries for the three age groups and in any crash type. The
analysis indicates that children involved in rollover crashes had the highest incidence rates of
incapacitating injuries. In rollover crashes, the estimated incidence rate of incapacitating injuries
among unrestrained children was almost three times that for restrained children. In near-side
impacts, unrestrained children were eight times more likely to sustain incapacitating injuries than
children restrained in child safety seats.
Head injuries were the most common injuries sustained by children in motor vehicle crashes.
Children under 1 year old had higher incidence rates of head injuries than the other two age
groups. Similar to head injuries, children under 1 had higher incidence rates of thoracic injuries
than the other two age groups.
Cerebrum injuries (contusions or lacerations) were the most common type of head injuries
among all children included in the analysis. Concussion and unconsciousness were more
common among children under 1 than the other two age groups. Skull base fractures were more
common among children 1 to 3 and 4 to 7 years old than children under 1 year old.
Children under 1 year old were more likely to sustain rib fractures than the other two age groups.
On the other hand, lung injuries (contusions or lacerations) were more common among older
children than children under 1 year old.
1
1. OBJECTIVE
Objectives: Analyze the incidence rates of incapacitating injuries as well as the commonly
injured body regions among children less than 8 years old involved in motor vehicle traffic
crashes.
2. INTRODUCTION
Injuries suffered in a motor vehicle traffic crashes are the leading cause of death among children
in the United States.5 Studies have shown that children who are correctly using the appropriate
restraint for their sizes and ages are at a significantly lower risk of sustaining serious or fatal
injuries.
The injury outcome in children can be worse than similar injuries sustained by adults. For
example, children who suffer traumatic brain injuries can experience lasting or late-appearing
neuropsychological problems, highlighting the need for careful monitoring of children as they
grow older.4 For this reason, head injuries are of particular concern when studying children
injured in motor vehicle traffic crashes.
In children, some neurological deficits after head trauma may not manifest for many years.2
Frontal lobe functions, for example, develop relatively late in a child's growth, so that injury to
the frontal lobes may not become apparent until the child reaches adolescence when higher level
reasoning develops. Since the frontal lobes control social interactions and interpersonal skills,
early childhood brain damage may not manifest until such frontal lobe skills are called into play
later in development. Likewise, injury to reading and writing centers in the brain may not
become apparent until the child reaches school age and shows signs of delayed reading and
writing skills.
3. DATA AND METHODOLOGY
This study provides a statistical analysis of two different databases:
1- The National Automotive Sampling System (NASS) General Estimates System (GES) for
1999 to 2008. NASS-GES is a complex probability sample of police-reported traffic crashes that
occurred in a given year.6 The NASS-GES data can be weighted to produce national estimates.
The weights result from the probabilities associated with each stage of selection, reflecting that
crash's probability of selection. NASS-GES reports injuries with different severity levels. The
injuries are reported based on the police reports as: no injury (O), possible injury (C), nonincapacitating injury (B), incapacitating injury (A), fatal injury (K), injured - severity unknown,
died prior to crash, or unknown if injured. NASS-GES is used to identify incidence rates of
incapacitating injuries in different crash scenarios and estimate effectiveness of child safety seat
use. Potential misuse scenarios of the child safety seat were not identified in this analysis, which
could skew some of the data findings toward higher injuries than if the child safety seats or seat
belts had been properly used.
2- The American College of Surgeons (ACS) was awarded a contract from the National Center
for Injury Prevention and Control (NCIPC), Centers for Disease Control and Prevention (CDC)
to develop a nationally-representative sample of the trauma centers that provided data on treated
2
trauma patients. This report provides analysis of the National Trauma Data Bank-National
Sample Program (NTDB-NSP) for 2003 to 2007. NTDB-NSP is a unique database that includes
clinical and resource information for a nationally representative sample of trauma incidents.1
NTDB-NSP is a stratified sample based in large part on existing NTDB data. Researchers can
use the NTDB-NSP to produce national estimates of trauma care. For privacy reasons, the
NTDB-NSP excludes data elements that could directly or indirectly identify individuals or
individual trauma centers.
To establish the NTDB-NSP, a stratified sample design was used, and 100 level I and level II
hospitals were included. Stratification was based on U.S. Census region (four regions), level of
trauma care designation (two categories), and NTDB reporting status (two categories). Thus,
there were 16 total strata: 8 NTDB strata and 8 non-NTDB strata. Of the 100 sample hospitals,
90 were allocated to the known NTDB-contributing hospitals and 10 to non-NTDB hospitals.
The sample size of 100 hospitals was chosen on the basis of recent NTDB data that suggested
that a sample of 100 hospitals would provide estimates having sufficient precision for most
analyses at the national level.
In the NTDB-NSP, motor vehicle occupants involved in passenger vehicle crashes were
identified by using the International Classification of Diseases, External Cause of Injury, Ninth
Revision (ICD-9 E-Codes) between 810.1 and 819.1. Information on external causes of injury is
coded and entered into the state’s electronic hospital discharge data system (HDDS) or hospital
emergency department data system (HEDDS).7 Although the NTDB-NSP provides detailed
medical and demographic information about these injured occupants, it lacks the information on
crash characteristics such as crash direction, crash severity, and manner of collision. Information
on child seating locations inside the vehicle is not available in NTDB-NSP data.
Cases not admitted to trauma centers are not included in the NTDB-NSP, including injury
victims who died before they can be transported to a hospital.
The analysis of both NASS-GES and NTDB-NSP were run separately without any linkage
between the two databases. The NTDB-NSP database was used due to the lack of medical
information in the NASS-GES database. The AIS 2+ injuries in NTDB-NSP are likely coded as
incapacitating injuries in NASS-GES.
When analyzing NTDB-NSP, only patients aged 0 through 7 years old with Abbreviated Injury
Scale (AIS) severity of 2 (moderate) or higher injuries were included3. Among vehicle occupants
who sustained AIS 2+ injuries, the injury or injuries with highest AIS for each body region were
selected for analysis. For example, a child with three head injuries of AIS 2, 3 and 4 and lower
extremity injuries of AIS 2 and 3, both the head injury with AIS 4 and the lower extremity injury
with AIS 3 were included in the analysis.
Injury severity in this study was identified through using the Abbreviated Injury Scale (AIS).
The AIS is an anatomical scoring system first introduced in 1969.3 AIS has been revised and
updated against survival to provide and accurate measure of injury severity ranking. Injuries are
ranked on a scale of 1 to 6, with 1 being minor, 5 severe, and 6 an unsurvivable injury.
3
Examples of injury AIS coding:
Skin contusion = AIS-1; Minor contusion of liver = AIS-2; Fractured femur = AIS-3
Flail chest= AIS-4; Complex rupture spleen =AIS-5
Children in this analysis were grouped into three age groups (less than one year, 1 to 3 years and
4 to 7 years) according to the age-appropriate type of child safety seat. The analysis is limited to
children involved in crashes involving passenger cars, minivans and light trucks. To account for
the sample design and its associated standard errors, the Statistical Analysis System (SAS)
version 9.1 Complex Sample Surveys was used to measure the confidence interval (CI) when
applicable.
Both NASS-GES and NTDB-NSP estimates are based on a national probability samples.
4. RESULTS
4.1. ANALYSIS OF POLICE-REPORTED CRASHES FROM NASS-GES
Seating Position of Children in Vehicles
Seating positions were grouped as first row and second row and rearward. Second row and
rearward refers to children who were seated in the second or third rows inside the vehicle (e.g.
minivans and some SUVs).
There was a noticeable variation on the seating positions inside the vehicle across the three age
groups. As shown in Table 1 and Figure 1, 31 percent (95% CI 28%-33%) of the children less
than 1 year old were seated on the center seat of the second row and rearward. Conversely, only
20 percent (95% CI 19%-22%) and 14 percent (95% CI 13%-15%) of children 1 to 3 and 4 to 7
years old were seated in the center seat of the second row and rearward, respectively. A higher
percentage (14%) of children 4 to 7 years old were seated on the front right seat, compared to the
other two age groups.
4
Table 1: Estimated Distribution of Seating Position in Vehicles for Child Passengers
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Seating Position
First row/center seat
Estimated
Count
13,233
First row/right
38,988
First row/unknown
Second row &
rearward/left
Second row &
rearward/center seat
Second row and
rearward/right
Second row &
rearward/unknown
2,265
149,277
194,695
200,053
11,288
Unknown
21,019
Total
630,819
(%)
2%
Estimated
Count
37,556
CI (1.5%-2.7%)
6%
CI (1%-2%)
6%
151,339
CI (5.1%-7.3%)
<1%
14,484
CI (0.2%-0.6%)
24%
802,078
CI (22%-25%)
31%
534,264
CI (28%-33%)
32%
933,744
CI (30%-34%)
2%
CI (5%-7%)
<1%
CI (0.4%-0.7%)
31%
CI (30%-32%)
20%
CI (19%-22%)
36%
CI (34%-37%)
57,621
CI (1.2%-2.4%)
3%
83,121
CI (2.5%-4.1%)
100%
(%)
1%
2,614,206
Source: NASS-GES 1999-2008
5
2%
CI (1%-3%)
3%
CI (2%-4%)
100%
Estimated
Count
61,013
426,486
13,856
978,895
427,188
970,208
82,461
94,546
3,054,653
(%)
2%
CI (2%-3%)
14%
CI (13%-15%)
<1%
CI (0.3%-0.6%)
32%
CI (31%-34%)
14%
CI (13%-15%)
32%
CI (30%-33%)
3%
CI (2%-4%)
3%
CI (2.5%-4%)
100%
Injury Severity
The vast majority of the children included in NASS-GES between 1999 and 2008 sustained no or
minor injuries. As seen in Table 2, only 1 percent of the children under 1 year old, 1 percent of
the children 1 to 3 years old, and 2 percent of children 4 to 7 years old sustained incapacitating
injuries.
Table 2: Estimated Distribution of Injury Severity by Child Passenger Age Involved
in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Injury Severity
No Injury
Possible Injury
Non-incapacitating
Injury
Incapacitating Injury
Fatal Injury
Injured, Severity
Unknown
Unknown if Injured
Total
Estimated
Count
545,786
51,204
12,177
7,572
979.957
2,031
11,069
630,819
Estimated
(%)
87%
CI (84%-89%)
8%
CI (7%-9%)
2%
CI (1.6%-2.3%)
1%
CI (0.1%-2.3%)
<1%
CI (0.01%-0.3%)
<1%
CI (0.1%-0.5%)
2%
CI (1.1%-2.4%)
100%
Estimated
Count
2,249,267
215,772
84,993
30,500
1,719
6,026
25,929
Estimated
(%)
Estimated
Count
Estimated
(%)
86%
83%
CI (84%-88%)
2,528,615
CI (80%-85%)
8%
10%
CI (7%-10%)
313,632
CI (9%-12%)
3%
4%
CI (2.8%-3.7%)
132,210
CI (3.8%-5%)
1%
2%
CI (0.1%-2.2%)
47,521
CI (0.4%-2.8%)
<1%
<1%
CI (0.01%-0.1%)
2,348
CI (0.0%-0.1%)
<1%
<1%
CI (0.1%-0.3%)
6,960
CI (0.1%-0.3%)
1%
1%
CI (0.7%-1.3%)
23,366
3,054,653
CI (0.5%-1.2%)
2,614,206
100%
100%
Source: NASS-GES 1999-2008
Incidence of Incapacitating Injuries in Different Crash Scenarios:
This section provides information of incidence rates of incapacitating injuries in relation to the
initial point of impact (IPI), seating position inside the vehicle and use of child safety seats. To
examine the incidence of incapacitating injuries in relation to the IPI and seating positions, the
IPI and seating positions were grouped into nine groups as shown in Table 3. Children who were
involved in rollovers and were seated in any seating position inside the vehicle were grouped as
Rollover. Children who were involved in rear impacts were grouped into two groups (1) Rear
Impact/First Row and (2) Rear Impact/Second Row and rearward. Children who were involved
in frontal impacts were grouped into two groups (1) Children seated in the first row “Frontal
Impact/First row” (2) Children seated in the second row and rearward “Frontal Impact/Second
Row and Rearward.” Children who were involved in side impacts were grouped into three
groups (1) Near-Side Impact (2) Far-Side Impact (3) Side Impact/Center seat (Table 3).
6
Table 3: Seating Position and Initial Direction of the Impact (IPI)
Initial Direction Of
Impact (IPI)
Seating Position
IPI/Seating Position
Right
Left
Right
Left
Frontal
Frontal
Rear
Rear
Side Impact
Rollover
Right (Any Row)
Left (Any Row)
Left (Any Row)
Right (Any Row)
First Row
Second Row +
First Row
Second Row +
Center seat (Any Row)
Any Seating Position
Near-Side Impact
Near-Side Impact
Far-Side Impact
Far-Side Impact
Frontal Impact/First Row
Frontal Impact/Second Row & Rearward
Rear Impact/First Row
Rear Impact/Second Row& Rearward
Side Impact/Center Seat
Rollover
Injury Severity by Initial Point of Impact (IPI)
Overall, vehicle’s front, rear and side were the most common IPI in all crashes involving
children 0 through 7 years old. Rollovers comprised only 2 percent of the crashes involving
children under 1 year old, 1 to 3 years old, and 4 to 7 year old, respectively (Table 4a). However,
rollovers had the highest incidence rates of incapacitating injuries with no significant difference
between the three age groups. An estimated 11 percent (95% CI 3% - 19%), 9.6 percent (95% CI
1% - 18%), and 15 percent (95% CI 6% - 24%) of children less than 1 year old, 1 to 3 years old,
and 4 to 7 years old who were involved in rollover crashes sustained incapacitating injuries,
respectively (Table 4b and Figure 2).
Children who were involved in frontal impacts and were seated in the front seats were twice as
likely to sustain incapacitating injuries as children who were seated in the second row and
rearward (Table 4b and Figure 2).
There was no significant difference in the incidence rates of incapacitating injuries for children
involved in different seating positions in rear crashes.
7
Table 4a: Estimated Distribution of IPI + Seating Position by Child Passengers Age
Involved in Motor Vehicle Crashes
Age
< 1 Year
1 to 3 Years
4 to 7 Years
IPI+ Seating Position
Frontal Impact/First
Row
Frontal Impact/Second
Row & Rearward
Near-Side Impact
Far-Side Impact
Side Impact/Center
Seat
Rear Impact/First Row
Rear Impact/Second
Row & Rearward
Rollover
Other/Unknown
Total
Estimated
Count
25,948
234,011
61,591
52,657
58,638
9,016
145,601
12,965
30,392
630,819
Estimated
(%)
Estimated
Count
4%
94,139
CI (3.2%-5%)
37%
CI (35%-39%)
10%
CI (9%-11%)
8%
CI (7%-10%)
9%
CI (8%-11%)
1,007,921
280,626
259,128
145,111
1%
42,773
CI (1%-2%)
23%
CI (21%-25%)
598,197
2%
49,932
CI (1.5%-3%)
5%
CI (4%-6%)
100%
Estimated
(%)
Estimated
Count
4%
234,943
CI (3.1%-4.1%)
39%
CI (38%-40%)
11%
CI (10%-11.4%)
10%
CI (9%-11%)
6%
CI (5%-6.2%)
1.6%
CI (1.3%-1.9%)
23%
CI (21%-25%)
2%
CI (1.5%-2.3%)
136,380
2,614,206
Source: NASS-GES 1999-2008
8
5%
CI (4%-6%)
100%
1,025,369
343,830
328,505
149,325
104,390
649,529
52,974
165,788
3,054,653
Estimated
(%)
8%
CI (7%-9%)
34%
CI (33%-35%)
11%
CI (10.6%-12%)
11%
CI (10%-11.3%)
5%
CI (4.5%-5.3%)
3.4%
CI (3%-4%)
21%
CI (20%-23%)
2%
CI (1.4%-2.1%)
5%
CI (4%-7%)
100%
Table 4b: Estimated Incidence Rates of Incapacitating Injuries by IPI by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
IPI+ Seating Position
Count
(%)
Count
(%)
Count
(%)
2%
2.7%
2%
1,904
6,320
530
Frontal Impact/First Row
CI (1%- 3%)
CI (1%-4.5%)
CI (0.3% - 3.8%)
Frontal Impact/Second
Row & Rearward
Near-Side Impact
2,176
914
1%
860
CI (0.0%-2%)
3,420
1.5%
CI (0.0% - 3.4%)
Far-Side Impact
1%
9,694
CI (0.1%-1.8%)
1.2%
552
3,722
1.6%
1.4%
1,763
1%
44
Rear Impact/Second Row
& Rearward
864
Rollover
1,416
1.2%
0.5%
278
0.6%
0.7%
CI (0.1% - 1.3%)
2,933
CI (0.0% - 1.3%)
4,791
11%
CI (3% - 19%)
Other/Unknown
213
1,994
0.7%
2,245
9.6%
1.50%
745
3,434
7,943
Source: NASS-GES 1999-2008
9
CI (0.1%-2.2%)
1.5%
1%
CI (0.1% - 1.3%)
0.5%
CI (0.0% - 1%)
15%
CI (6% - 24%)
2,502
1.5%
CI (1% - 2.2%)
1%
30,500
CI (0.1%-2.3%)
2%
CI (0.1% - 3%)
CI (1% - 2%)
1%
7,569
0.5%
CI (0.1% - 1%)
1.6%
CI (0.3%-3.8%)
CI (1% - 18%)
CI (0.1% - 1.4%)
Total
6,743
CI (0.0% - 2.7%)
CI (0.0% - 1.4%)
1.2%
CI (0.1%-2.2%)
CI (0.4% - 2.8%)
CI (0.0%-2.9%)
CI (0.1% - 1.8%)
Rear Impact/First Row
5,563
CI (0.1% - 2.3%)
CI (0.0%-3.6%)
Side Impact/Center Seat
12,026
2%
47,521
CI (0.4%-2.8%)
Injury Severity by Restraint Use
Overall, in this analysis, the rate of child safety seat use in police-reported crashes varied from
85 percent (95% CI 83%-88%) among children less than 1 year old to only 24 percent (95% CI
21%-27%) among children 4 to 7 years old. A large proportion of the children 4 to 7 years old
(48%, 95% CI 43%-52%) were using lap and shoulder belts (Table 5a).
The incidence rate of incapacitating injuries was lower among children restrained in child safety
seats. As shown in Table 5b and Figure 3, incapacitating injuries were sustained by 8 percent
(95% CI 2%-13%), 7 percent (95% CI 2.5%-11%), and 7 percent (95% CI 2.6%-12%) of
children less than 1 year, 1 to 3 years and 4 to 7 years old who were not in child safety seats and
did not use lap/shoulder belts, respectively. Conversely, only 1.1 percent (95% CI 0.0%-2.2%) , 1
percent (95% CI 0.0%-2%), and 1 percent (95% CI 0.2%-2%) of children less than 1 year, 1 to 3
years and 4 to 7 years old who used child safety seats sustained incapacitating injuries,
respectively.
The breakdown percent distribution of the other/unknown category of restraint system use is
provided in Table 5c.
10
Table 5a: Estimated Distribution of the Police-reported Child Safety Seat Use by Child Passengers Age
Involved in Motor Vehicle Crashes
Age
< 1 Year
1 to 3 Years
4 to 7 Years
Restraint
Systems
Estimated
Count
(%)
Child Safety Seat
Lap and Shoulder
Belt
537,142
CI (83%-88%)
28,160
CI (3.5%-5.5%)
None Used
14,239
CI (1.8%-2.7%)
Other/Unknown*
51,279
CI (6%-10%)
Total
630,819
100%
Estimated
Count
(%)
1,919,191
CI (71%-76%)
328,772
CI (11%-14%)
84,310
CI (2.7%-3.7%)
281,928
2,614,202
CI (9%-13%)
Estimated
Count
(%)
722,731
CI ( 21%-27%)
1,454,340
CI (43%-52%)
128,362
CI (3.6%-4.8%)
748,954
3,054,386
CI (20%-29%)
73%
85%
24%
13%
4%
48%
3%
2%
8%
4%
25%
11%
100%
100%
Source: NASS-GES 1999-2008
Table 5b: Estimated Incidence Rates of Incapacitating Injuries by Police-reported Child Safety Seat Use and Child
Passengers Age Involved in Motor Vehicle Crashes
Age
< 1 Year
1 to 3 Years
4 to 7 Years
Estimated
Count
(%)
5,822
CI (0.0%-2.2%)
Lap and Shoulder Belt
439
CI (0.0%-3%)
None Used
1081
CI (2%-13%)
Other/Unknown
229
CI (0.0%-0.5%)
7,569
CI (0.1%-2.3%)
Restraint Systems
Estimated
Count
(%)
17,026
CI (0.0%-2%)
3,737
CI (0.3%-2%)
5,768
CI (2.5%-11%)
3,968
CI (0.6%-2.2%)
30,500
CI (0.1%-2.2%)
1.5%
7,540
CI (0.2%-2%)
21,120
CI (0.2%-2.7%)
9,199
CI (2.6%-12%)
9,662
CI (0.4%-2.0%)
47,521
CI (0.4%-2.8%)
1%
1.1%
8%
1.5%
7%
0.4%
7%
1.4%
1%
Total
(%)
1%
1.1%
Child Safety Seat
Estimated
Count
1.3%
1%
2%
Source: NASS-GES 1999-2008
Table 5c: Details of Other/Unknown Category of Restraint System Use
RESTRAINT SYSTEM USE
Lap Belt
Shoulder Belt
Restraint Used-Specifics
Unknown or Other
Unknown if Used
Total
< 1 Year
1 to 3 Year
4 to 7 Year
0.5%
0.1%
3.5%
0.2%
11%
0.5%
3.4%
3.9%
3.7%
3.2%
10%
4%
8%
11%
25%
Source: NASS-GES 1999-2008
11
Injury Severity by Restraint Use and Initial Point of Impact (IPI)
The information provided in this section examines the incidence rates of incapacitating injuries
for the three age groups combined. The use of child safety seats reduced the incidence rates of
incapacitating injuries for the three age groups and all crash types. As shown in Table 6b and
Figure 4, children involved in rollover crashes had the highest incidence rates of incapacitating
injuries.
Unrestrained children had significantly higher rates of incapacitating injuries regardless of their
seating position inside the vehicles. As shown in Table 6b, the incidence rates of incapacitating
injuries were 7 percent (95% CI 2%-12%) and 6.5 percent (95% CI 0.0%-13%) for children
involved in frontal crashes and were seated in the first row and second row and rearward,
respectively, compared with 1 percent (95% CI 0.1%- 1.6%) and 1 percent (95% CI 0.0%1.7%) for children restrained children involved in frontal crashes and seated in the first row and
second row and rearward, respectively.
In rollover crashes, the estimated incidence rate of incapacitating injuries among unrestrained
children was 26 percent (95% CI 14%-37%) compared with 9 percent (95% CI 0.4%-18%)
among children restrained in child safety seats and 10 percent (95% CI 1.1%-19%) among
children who used lap and shoulder belts.
Unrestrained children had significantly higher rates of incapacitating injuries in side impacts than
restrained children. Incidence rates of incapacitating injuries were 8 percent (95% CI 5%-12%),
6.5 percent (95% CI 1%-12%), and 7 percent (95% CI 2%-13%) for unrestrained children
involved in near-side impacts, far-side impacts and side impacts/center seat, respectively,
compared with 1 percent (95% CI 0.1%-2%), 1.3 percent (95% CI 0.0%-2.7%), and 1 percent
12
(95% CI 0.0%-2%) for restrained children involved in near-side impacts, far-side impacts and
side impacts/center seat, respectively.
Restraint
Systems
IPI+ Seating
Position
Frontal Impact/
First Row
Frontal
Impact/Second
Row & Rearward
Near-Side
Impact
Far-Side
Impact
Side Impact/
Center Seat
Rear Impact/
First Row
Rear
Impact/Second
Row & Rearward
Rollover
Other/Unknown
Total
Table 6a: Estimated Distribution of IPI by Restraint Systems Use for Child Passengers
Involved in Motor Vehicle Crashes
Child Safety Seat
Lap & Shoulder
None Used
Other/Unknown
Estimated
Count
77,166
Estimated
(%)
2.5%
CI (2.1%- 2.8%)
Estimated
Count
180,588
Estimated
(%)
10%
CI (9%-11%)
337,226
311,128
185,158
36,478
CI (39%- 41%)
11%
CI (10%- 11.2%)
10%
572,927
239,063
CI (30%- 33%)
13%
CI (12%-14%)
13%
229,568
59,198
108,737
3,179,064
Estimated
(%)
12%
CI (10%-15%)
19,046
17,996
CI (27%-34%)
8%
CI (7%-10%)
8%
CI (12%- 14%)
CI (7%-9%)
6%
2%
7%
CI (5%- 7%)
1%
CI (0.9%- 1.4%)
38,820
84,576
CI (1.8%-2.5%)
5%
CI (4-5%.1%)
CI (23%- 27%)
2%
CI (1.5%- 2.3%)
3%
CI (2.6%- 4%)
100%
15,551
6,497
20%
354,682
26,842
84,205
CI (18%-21%)
1.5%
CI (1.2%- 1.8%)
5%
CI (3%-6%)
1,811,272
100%
Source: NASS-GES 1999-2008
13
Estimated
Count
69,366
31%
69,481
CI (9%- 10.2%)
25%
793,909
27,906
32%
40%
1,270,065
Estimated
Count
CI (6%-8%)
3%
CI (2%-4%)
12,947
31,530
226,910
CI (9%-14%)
6%
CI (5%-7%)
14%
CI (11%-17%)
100%
6%
CI (5.5%-7%)
33%
354,823
90,712
81,598
CI (31%-34%)
8%
CI (7%-10%)
8%
CI (6%-9%)
113,545
28,366
11%
25,957
Estimated
(%)
10%
CI (9%-12%)
3%
CI (2-3%.2%)
20%
218,779
16,885
108,087
1,082,161
CI (19%-22%)
1.8%
CI (1%-2%)
10%
CI (8%-12%)
100%
Table 6b: Estimated Incidence Rates of Incapacitating Injuries by IPI and Restraint Systems Use for Child Passengers
Involved in Motor Vehicle Crashes
Restraint
Child Safety Seat
Lap & Shoulder
None Used
Other/Unknown
Systems
IPI+ Seating
Estimated
Estimated
Estimated
Estimated
Estimated Estimated Estimated
Estimated
Position
Count
(%)
Count
(%)
Count
(%)
Count
(%)
Frontal
Impact/First Row
Frontal
Impact/Second
Row & Rearward
Near-Side Impact
Far-Side Impact
Side
Impact/Center
Seat
674
1%
CI (0.1%- 1.6%)
4,328
Rollover
Other/Unknown
Total
CI (1%-4%)
10,280
3,352
3,933
CI (0.0%- 1.7%)
1%
CI (0.1%- 2%)
1.3%
5,372
3,965
416
CI (0.0%-2.4%)
5,475
893
30,388
CI (0%-1%)
9%
CI (0.4%- 18%)
1%
CI (0.1%- 1.5%)
1%
CI (0.0%-2%)
2%
4,544
1,544
1,161
CI (0.0 %-1.5%)
CI (0.1% –
1.3%)
2,709
814
25,297
CI (0.1%- 1.2%)
10%
CI (1.1%- 19%)
1%
CI (0.3% -1.6%)
1.4%
CI (0.2%-2.6%)
Source: NASS-GES 1999-2008
14
8%
CI (5%-12%)
6.5%
CI (2%-13%)
CI (0.0%-3%)
1037
1185
3,353
1,735
16,048
CI (0.0%-4%)
26%
CI (14%-37%)
6%
CI (2.4%-9%)
7%
CI (3%-12%)
CI (1%-4%)
CI (0.5%-1.6%)
1%
CI (0.2%-2%)
1.4%
CI (0.6%-2%)
0.7%
1265
CI (0.0%-2.5%)
0.1%
30
2%
445
2.5%
1%
3700
1%
71
0.6%
2,299
CI (0.0% 13%)
7%
1,167
0.6%
549
CI (2%-12%)
1726
CI (1%-12%)
0.5%
215
0.4%
3,450
2%
CI (0.0%-3%)
7%
6.5%
CI (0.2%- 4%)
1%
CI (0.0%-2%)
CI (0.1%- 2%)
5,045
CI (0.0-% 2.7%)
1,913
2,027
1%
1%
1.2%
Rear Impact/First
Row
Rear
Impact/Second
Row & Rearward
2.4%
CI (0.0%.0.2%)
0.5%
1038
2613
1266
13,859
CI (0.0%-1%)
15%
CI (6%-25%)
1%
CI (0.5%-2%)
1.3%
CI (0.5%-2%)
4.2. ANALYSIS OF NTDB-NSP DATA
An estimated 1,731 children under 1 year old, 4,062 children between 1 to 3 years old, and 6,339
children between 4 to 7 years old were identified in NTDB-NSP dataset between 2003 and 2007.
An estimated 1,188 (69%), 2,319 (57%), and 4,169 (66%) of the children under 1 year old, 1 to 3
years old, and 4 to 7 years old had Maximum Abbreviated Injury Scale (MAIS) 2+, respectively
(Table 7).
15
Table 7: Estimated Incidence Rates of MAIS by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
Count
MAIS
Estimated
Count
Unweighted
103
MAIS-1
487
MAIS-2
383
69
MAIS-3
454
93
MAIS-4
215
69
MAIS-5
126
27
MAIS-6
10
Unknown
56
Total
1,731
MAIS 2+
1,188
Estimated
Estimated (%)
28%
22%
CI (18%-26%)
26%
CI (22%-30%)
12%
CI (9%-16%)
7%
CI (2%-13%)
3
1%
CI (0.0%-1.4%)
18
3%
CI (1.2%-5.3%)
382
100%
68%
Count
Unweighted
Estimated (%)
397
1,664
CI (23%-33%)
41%
CI (36%-46%)
959
289
865
236
375
104
116
45
24%
CI (20%-27%)
21%
CI (19%-24%)
9%
CI (7%-11%)
3%
CI (2%-4%)
2
4
0%
--
42
79
2%
CI (0.4%-3%)
1,115
4,062
4 to 7 Years
2,319
Estimated
2,027
Estimated (%)
Unweighted
515
2,024
505
1,209
374
704
196
225
76
7
143
100%
6,339
57%
4,169
32%
CI (27%-37%)
32%
CI (29%-35%)
19%
CI (16%-22%)
4%
CI (2%-5%)
5
0%
--
52
2%
CI (1%-4%)
1,723
Source: NTDB-NSP 2003-2007
The estimates may not sum to the totals due to rounding
Injuries by Body Region
In this section the percentages are calculated as the total number of children who sustained
certain type of AIS 2+ injury divided by the total number of children who had MAIS of 2+
within each age group. For example, a total of 1,188 children under 1 year old sustained MAIS
2+ injuries and of those, 827 sustained AIS 2+ head injuries. The incidence rate of head injuries
among this age group = 827/1,188 X 100 or 70 percent.
As shown in Table 8 and Figure 4, the head was the most common body region injured in motor
vehicle crashes for the three age groups included in the analysis. However, children under 1 year
old had a higher percent of AIS 2+ head injuries at 70 percent as compared to 51 percent and 39
percent among children 1 to 3 years and 4 to 7 years old, respectively. Thoracic injuries were
noticeably higher among children under 1 year old at 31 percent when compared to 14 percent
and 12 percent among children 1 to 3 years and 4 to 7 years old, respectively.
Similar to thoracic injuries, spine injuries were noticeably higher among children under 1 year
old at 16 percent when compared to 4 percent and 5 percent among children 1 to 3 years and 4 to
7 years old, respectively.
16
11%
CI (9%-13%)
100%
66%
Table 8: Estimated Incidence Rates of AIS 2 + Injuries by Body Region and Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Estimated
Count
Unweighted
Body Region
827
163
Head
369
63
Thorax
Lower
Extremity
218
34
Abdomen
Spine
Upper
Extremity
Face
205
192
182
57
36
37
35
12
Count
Estimated
(%)
Estimated
Unweighted
70%
1,189
321
31%
334
94
18%
412
111
17%
217
16%
84
15%
196
5%
168
55
26
52
47
Estimated
(%)
Estimated
51%
1,640
449
14%
481
156
18%
707
192
9%
694
4%
226
8%
600
7%
445
Source: NTDB-NSP 2003-2007
Note: Percents do not add to 100% as one occupant might sustain more than one injury
17
Unweighted
202
57
147
102
Estimated
(%)
39%
12%
17%
17%
5%
14%
11%
Injury Diagnosis
This section provides the frequency distribution of injury diagnosis for different body regions.
Some injuries were grouped into one category due to their relevancy, such as small and large
bowel injuries, lung contusion and laceration, cerebrum contusion and laceration, etc.
1- Head Injuries
Cerebrum injuries (contusions or lacerations) were the most common type of head injuries
among all children included in the analysis. Concussions/unconsciousness were more common
among children under 1 year old, when compared to the other 2 groups. Skull base fractures were
more common among children 1 to 3 and 4 to 7 years old when compared to children under 1
year old (Table 9).
Table 9: Estimated Distribution of AIS 2+ Head Injuries by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Cerebrum
Injury
Skull Vault
Fracture
Unconsciousness/
Concussion
Subarachnoid
Hemorrhage
Subdural
Hematoma
Skull Base
Fracture
Estimated
Unweighted
300
62
Count
Estimated
(%)
Estimated
Unweighted
26%
561
148
CI (19%-32%)
234
42
20%
215
46
18%
361
87
34
14%
156
58
31
10%
143
43
15
6%
144
42
6%
848
227
21%
9%
34%
CI (28%-40%)
489
102
20%
CI (17%-23%)
272
90
11%
8%
CI (6%-16%)
218
52
9%
8%
CI (6%-12%)
184
46
7%
CI (5%-12%)
222
49
CI (3%-9%)
19
33%
Estimated
(%)
CI (6%-11%)
CI (6%-14%)
69
Unweighted
CI (4%-14%)
CI (10%-17%)
120
Estimated
CI (18%-25%)
CI (6%-30%)
159
Estimated
(%)
CI (25%-40%)
CI (11%-29%)
74
Other
Count
13%
CI (5%-10%)
303
82
CI (9%-17%)
128
34
CI (2%-9%)
7%
12%
CI (10%-14%)
169
49
CI (3%-11%)
Source: NTDB-NSP 2003-2007
2- Thoracic Injuries
Rib fractures were more common among children under 1 year old (37%, 95% CI 22%-52%)
when compared to the other two age groups. On the other hand, lung injuries (contusions or
lacerations) were more common among children 1 to 3 and 4 to 7 years old when compared to
children under 1 year old (Table 10).
18
6%
CI (5%-9%)
Table 10: Estimated Distribution of AIS 2+ Thoracic Injuries by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Injury Type
Count
Estimated
Unweighted
214
32
Rib Fracture
Estimated
Unweighted
37%
36
11
CI (22%-52%)
194
Lung Injury
Thoracic
Cavity Injury
Count
Estimated
(%)
32
82
CI (25%-42%)
121
20
19
CI (10%-32%)
50
7
Other
8%
86
23
65%
20%
3
CI (3%-14%)
6%
Estimated
(%)
14%
CI (10%-18%)
415
137
67%
CI (61%-72%)
93
31
CI (13%-28%)
27
8%
Unweighted
CI (55%-74%)
86
21%
Estimated
CI (5%-12%)
276
33%
Estimated
(%)
15%
CI (10%-20%)
28
8
4%
CI (1%-12%)
CI (1%-8%)
Source: NTDB-NSP 2003-2007
3- Abdominal Injuries
Small-bowel injuries and large-bowel injuries were more common among children 4 to 7 years
old, accounting for 30 percent (95% CI 23%-37%) of all abdominal injuries compared to only 14
percent among children under 1 year old (CL 5%-23%) and 19 percent (CI 12%-26%) among
children 1 to 3 years old (Table 11).
Table 11: Estimated Distribution of AIS 2+ Abdominal Injuries by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Injury Type
Liver Injury
Count
Estimated
Unweighted
87
14
Estimated
(%)
32%
Estimated
Count
Unweighted
104
27
CI (23%-42%)
Spleen
Injury
Small/Large
Bowel Injury
Kidney
Injury
Other
67
15
25%
8
14%
124
30
6
15%
66
12
7
14%
30%
263
71
36%
19%
30
8
9%
268
22
6
6%
25%
73
26%
CI (20%-32%)
311
86
30%
CI (23%-37%)
122
31
CI (6%-11%)
CI (5%-23%)
Estimated
(%)
CI (21%-30%)
CI (12%-26%)
CI (5%-25%)
38
Unweighted
CI (27%-44%)
CI (5%-23%)
41
Estimated
CI (22%-38%)
CI (8%-42%)
38
Estimated
(%)
12%
CI (8%-15%)
70
23
CI (1%-12%)
Source: NTDB-NSP 2003-2007
4- Upper Extremity Injuries
Humerus fractures accounted for 43 percent (95% CI 33%-53%) of upper extremity injuries for
children 1 to 3 years old. Fracture radius and ulna combined (forearm) accounted for 26 percent,
24 percent and 35 percent for children under 1 year, 1 to 3 and 4 to 7 years old, respectively
(Table 12).
19
7%
CI (4%-9%)
Table 12: Estimated Distribution of AIS 2+ Upper extremity Injuries by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Injury Type
Estimated
Unweighted
59
12
Clavicle Fracture
Estimated
(%)
Count
Estimated
Unweighted
Estimated
Unweighted
25%
52
18
191
48
CI (12%-38%)
48
10
Humerus Fracture
20%
36
7
15%
107
22
25
5
11%
31
9
69
13
30
5
49
12%
12%
5
CI (0.0%-31%)
12%
29%
CI (24%-34%)
176
44
24%
CI (18%-30%)
82
21
CI (7%-17%)
30
6%
209
CI (5%-19%)
CI (0.2%-31%)
Other
43%
26%
CI (20%-32%)
CI (33%-53%)
CI (0.0%-31%)
Ulna Fracture
21%
CI (12%-30%)
CI (12%-29%)
Radius Fracture
Estimated
(%)
Count
Estimated
(%)
11%
CI (8%-15%)
72
22
CI (4%-20%)
10%
CI (6%-14%)
Source: NTDB-NSP 2003-2007
5- Lower Extremity Injuries
Pelvic fractures were higher among children under 1 year old when compared to the other two
age groups. Below knee injuries were higher among children 1 to 3 (37%, 95% CI 26%-48%)
and 4 to 7 years old (35%, 95% CI 27%-42%) compared with only 17 percent (95% CI 10%23%) among children under 1 year old (Table 13).
Table 13: Estimated Distribution of AIS 2+ Lower Extremity Injuries by Child Passengers Age
Involved in Motor Vehicle Crashes
< 1 Year
1 to 3 Years
4 to 7 Years
Count
Injury Type
Estimated
(%)
Estimated
Unweighted
111
19
Pelvis Fracture
Estimated
Unweighted
54
20
12
246
28%
55
9
61
51
CI (10%-23%)
10
Estimated
Unweighted
218
61
49%
37%
7
CI (18%-24%)
3%
CI (0.4%-6%)
Source: NTDB-NSP 2003-2007
20
23%
CI (17%-30%)
354
98
38%
CI 3(4%-41%)
327
80
CI (26%-48%)
15
22%
Estimated
(%)
CI (39%-60%)
184
17%
11%
Count
CI (6%-16%)
CI (12%-45%)
68
Other
Estimated
(%)
CI (24%-44%)
91
Femur Fracture
Tibia/Fibula
Fracture
34%
Count
35%
CI (27%-42%)
43
10
5%
CI (2%-7%)
CONCLUSION
This analysis demonstrates that the use of child safety seats are effective in reducing the
incidence rates of incapacitating injuries for the three age groups and in any motor vehicle traffic
crash type. All children involved in rollover crashes had the highest incidence rates of
incapacitating injuries. In rollover crashes, the estimated incidence rate of incapacitating injuries
among unrestrained children was almost three times that for restrained children. In near-side
impacts, unrestrained children were eight times more likely to sustain incapacitating injuries
when compared with children restrained in child safety seats.
The head injuries were the most common injuries sustained by children in motor vehicle crashes.
Children under 1 year old had higher incidence rates of head injuries when compared to the other
two age groups. Similar to head injuries, children under 1 year old had higher incidence rates of
thoracic injuries when compared to the other two age groups.
Cerebrum injuries (contusions or lacerations) were the most common type of head injuries
among all children included in the analysis. Concussion/unconsciousness were more common
among children under 1 year old, when compared to the other two groups. Skull base fractures
were more common among children 1 to 3 and 4 to 7 years old than children under 1 year old.
Children under 1 year old were more likely to sustain rib fractures than the other two age groups.
On the other hand, lung injuries (contusions or lacerations) were more common among older
children than children under 1 year old.
Small-bowel injuries and large-bowel injuries were more common among older children. Pelvic
fractures were higher among children under 1 year old when compared to the other two age
groups. Below-knee injuries were higher among older children.
The injury outcome in children can be worse than similar injuries sustained by adults.4 There is a
special need to prevent head injuries among children due to their long-term complications. For
example, children who suffer traumatic brain injuries can experience lasting or late-appearing
neuropsychological problems, highlighting the need for careful monitoring as they get older.
In children, some neurological deficits after head trauma may not manifest for many years.2
Frontal lobe functions, for example, develop relatively late in a child's growth, so that injury to
the frontal lobes may not become apparent until the child reaches adolescence as higher level
reasoning develops. Since the frontal lobes control our social interactions and interpersonal
skills, early childhood brain damage may not manifest until such frontal lobe skills are called
into play later in development. Likewise, injuries to reading and writing centers in the brain may
not become apparent until the child reaches school age and shows signs of delayed reading and
writing skills.
The information presented in this report aims to provide researchers, parents and policy makers
with statistics on children injured in motor vehicle traffic crashes, and it stresses the importance
of the using child safety seats.
21
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3. MacKenzie, E. J., Shapiro, S., & Eastham, J. N. (1985, June). the Abbreviated Injury
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